4Needs for Energy StorageSupply of most RE systems as well as energy demand are time dependent.Both RE supply and energy demand generally follow a statistical phenomenaAvailability of RE supply does not necessarily coincide with the energy demand

5Supply & Demand PatternPV Outputoutput to batteryoutput to loadload to be supplied from battery

17ConclusionStorage system remains an important component or plays an important role in distributed generation, particularly for the renewable energy system applications.Cost of RE distributed generation, particularly a stand-alone PV system, is significantly influenced by the cost of battery. Hence, there is a need to reduce the battery cost and increase the battery lifetime to enable bring both the investment- and lifecycle costs of renewable energy systems down.Hydraulic storage (pumped water) can be one of alternative energy storage system for RE application.Utilization of pumped sea water as a storage has an economic potential to be developed along the south-coast of Java island. It can be used to fill the valley during low demand of Java-Bali grid or in combination with the utilization of distributed renewable energy sources (wave, wind and solar-energy).